Apparatus and method for transmitting d2d data based on resource pattern

ABSTRACT

A method and apparatus for supporting a device-to-device (D2D) communication between user equipments (UEs) are provided. A method of transmitting device-to-device (D2D) data using a D2D data transmission resource by a user equipment (UE), the method including: receiving, at a UE, configuration information associated with a D2D data transmission resource, the configuration information including information of a D2D data allocation period and being transmitted from an evolved NodeB (eNB); determining, at the UE, a D2D data transmission resource in each D2D data allocation period, the D2D data transmission resource including a pool of subframes; selecting D2D data transmission subframes from among the pool of subframes based on a changed pattern, the changed pattern being derived from a basic pattern; and transmitting, from the UE to another UE, D2D data based on the selected D2D data transmission subframes.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. application Ser. No.14/820,461, filed on Aug. 6, 2015, which is continuation-in-part of U.S.application Ser. No. 14/819,232, filed on Aug. 5, 2015, and claimspriority from and the benefit of Korean Patent Application Nos.10-2014-0102572, filed on Aug. 8, 2014, and 10-2014-0102662, filed onAug. 8, 2014, all of which are hereby incorporated by reference in theirentirety.

BACKGROUND 1. Field

The present disclosure relates to wireless communication, and moreparticularly, to a method and apparatus for transmitting Device toDevice (D2D) data based on a resource pattern.

2. Discussion of the Background

An amount of data transmitted through wireless communication hasgradually increased. However, the frequency resources that serviceproviders can provide are limited and have become increasinglysaturated, and thus, mobile carriers continuously develop technologiesfor discovering new frequencies and improving efficient use offrequencies. One of the actively studied technologies to ease thefrequency resource shortage and to create a new mobile communicationservice is Device-to-Device (D2D) communication technology.

D2D communication refers to a technology in which User Equipments (UEs)which are geometrically adjacent to one another, directly transmit andreceive information without passing through an infrastructure, such as abase station. In the initial stage, the D2D communication technology wasdeveloped and standardized mostly in a non-licensed band such as Wi-Fi,Direct, Bluetooth, which have been already commercialized. However,recently, the development of technologies and standardization forsupporting D2D communication in a cellular system that uses a licensedband, are underway. Representatively, the 3^(rd) Generation PartnershipProject (3GPP), which is a mobile communication standardizationassociation, actively conducts D2D communication technologystandardization that is referred to as Proximity-based services (ProSe),which is one of the new technologies included in Long Term Evolution(LTE).

However, for the LTE wireless communication system, a method for usingdata resources for effectively providing D2D services has not beendetermined. Therefore, there is desire for a method of using resourcesfor effectively supporting services.

SUMMARY

Exemplary embodiments provide a method and apparatus for transmittingDevice to Device (D2D) data based on a resource pattern.

Exemplary embodiments provide a method and apparatus for transmittingdevice-to-device (D2D) data using a D2D data transmission resource.

An exemplary embodiment provides a method of transmittingdevice-to-device (D2D) data using a D2D data transmission resource by auser equipment (UE), the method including: receiving, at a UE,configuration information associated with a D2D data transmissionresource, the configuration information including information of a D2Ddata allocation period and being transmitted from an evolved NodeB(eNB); determining, at the UE, a D2D data transmission resource in eachD2D data allocation period, the D2D data transmission resource includinga pool of subframes; selecting D2D data transmission subframes fromamong the pool of subframes based on a changed pattern, the changedpattern being derived from a basic pattern; and transmitting, from theUE to another UE, D2D data based on the selected D2D data transmissionsubframes.

An exemplary embodiment provides a user equipment (UE) to transmitdevice-to-device (D2D) data using a D2D data transmission resource,including: a wireless transceiver configured to: receive configurationinformation associated with a D2D data transmission resource, theconfiguration information including information of a D2D data allocationperiod and being transmitted from an evolved NodeB (eNB); and one ormore processors configured to: determine a D2D data transmissionresource in each D2D data allocation period, the D2D data transmissionresource including a pool of subframes; and select D2D data transmissionsubframes from among the pool of subframes based on a changed pattern,the changed pattern being derived from a basic pattern. The wirelesstransceiver transmits, from the UE to another UE, D2D data based on theselected D2D data transmission subframes.

An exemplary embodiment provides a method of transmittingdevice-to-device (D2D) data using a D2D data transmission resource by auser equipment (UE), the method including: receiving, at a UE,configuration information associated with a D2D data transmissionresource, the configuration information being transmitted from anevolved NodeB (eNB); determining, at the UE, a D2D data transmissionresource, the D2D data transmission resource including a pool ofsubframes; and selecting D2D data transmission subframes from among thepool of subframes based on a changed pattern, the changed pattern beingdetermined based on (R mod X), wherein R corresponds to the number ofsubframes in the pool of subframes and X corresponds to a length of abasic pattern, where R and X are natural numbers; and transmitting, fromthe UE to another UE, D2D data based on the selected D2D datatransmission subframes. A length of the changed pattern corresponds toR.

A collision or interference between User Equipments (UEs) caused bytransmission and/or reception of Device-to-Device (D2D) data may bereduced or minimized based on assignment of D2D data resources used forD2D communication. Therefore, the performance of the D2D datatransmission may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual diagram illustrating a structure of a radio frameaccording to an exemplary embodiment.

FIG. 2 is a conceptual diagram illustrating a structure of a radio frameaccording to an exemplary embodiment.

FIG. 3 is a conceptual diagram illustrating D2D communication accordingto an exemplary embodiment.

FIG. 4 is a conceptual diagram D2D communication resources according toan exemplary embodiment.

FIG. 5 is a conceptual diagram D2D communication resources according toan exemplary embodiment.

FIG. 6 illustrates a method of determining selected D2D communicationresources according to an exemplary embodiment.

FIG. 7 is a conceptual diagram illustrating a T-RPT according to anexemplary embodiment.

FIG. 8 is a conceptual diagram illustrating a basic pattern according toan exemplary embodiment.

FIG. 9 is a table illustrating a basic pattern according to an exemplaryembodiment.

FIG. 10 is a table illustrating a basic pattern according to anexemplary embodiment.

FIG. 11 is a conceptual diagram illustrating a method of generating achanged pattern based on a basic pattern according to an exemplaryembodiment.

FIG. 12 is a conceptual diagram illustrating a method of generating achanged pattern based on a basic pattern according to an exemplaryembodiment.

FIG. 13 is a conceptual diagram illustrating a method of generating achanged pattern based on a basic pattern according to an exemplaryembodiment.

FIG. 14 is a flowchart illustrating an operation of transmitting trafficdata of a user equipment according to an exemplary embodiment.

FIG. 15 is a block diagram illustrating a base station and a userequipment according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Exemplary embodiments will be described more fully hereinafter withreference to the accompanying drawings, in which exemplary embodimentsof inventive concept are shown. Throughout the drawings and the detaileddescription, unless otherwise described, the same drawing referencenumerals are understood to refer to the same elements, features, andstructures. In describing the exemplary embodiments, detaileddescription on known configurations or functions may be omitted forclarity and conciseness.

Further, the terms, such as first, second, A, B, (a), (b), and the likemay be used herein to describe elements in the description herein. Theterms are used to distinguish one element from another element. Thus,the terms do not limit the element, an arrangement order, a sequence orthe like. It will be understood that when an element is referred to asbeing “on”, “connected to” or “coupled to” another element, it can bedirectly on, connected or coupled to the other element or interveningelements may be present. The present specification provides descriptionsin association with a wireless communication network, and tasks executedin the wireless communication network may be performed in the processwhere a system (for example, a base station) that manages thecorresponding wireless communication network controls the network andtransmits data, or may be performed in a User Equipment (UE) that iswireless linked to the corresponding network and capable ofcommunicating with the network system.

FIG. 1 is a conceptual diagram illustrating a structure of a radio frameaccording to an exemplary embodiment.

FIG. 1 illustrates a structure of a radio frame for Frequency DivisionDuplexing (FDD)-based Device-to-Device (D2D) communication.

Referring to FIG. 1, a radio frame may include ten subframes. A singlesubframe includes two slots. A time (a length) in which a singlesubframe is transmitted is referred to as a Transmission Time Interval(TTI). Referring to FIG. 2, for example, a length of a single subframe(1 subframe) may be 1 ms, and a length of a single slot (1 slot) may be0.5 ms.

A single slot may include a plurality of symbols in a time domain. Forexample, in a wireless system that uses Orthogonal Frequency DivisionMultiple Access (OFDMA) in a Downlink (DL), the symbol may be anOrthogonal Frequency Division Multiplexing (OFDM) symbol and in awireless system that uses Single Carrier-Frequency Division MultipleAccess (SC-FDMA) in an Uplink (UL), the symbol may be an SC-FDMA symbol.An expression associated with a symbol period of the time domain may notbe limited by a multiple access scheme or name.

The number of symbols included in a single slot may be different basedon a length of a Cyclic Prefix (CP). For example, in the case of anormal CP, seven symbols are included in a single slot, and in the caseof an extended CP, six symbols are included in a single slot.

For FDD, when two component carrier frequencies exist, the two componentcarrier frequencies may be used for uplink transmission and downlinktransmission, respectively. Hereinafter, from the perspective of asingle D2D User Equipment (UE) (hereinafter referred to as a UE) thatsupports predetermined D2D communication, uplink transmission refers todata transmission from the UE to another UE or to a Base Station (BS),and uplink data refers to data transmitted from the UE to the other UEor the BS. Also, from the perspective of the UE, downlink transmissionrefers to data transmission from another UE or a BS to the UE, anddownlink data refers to data transmitted from the other UE or the BS tothe UE.

For duplexing scheme-based FDD, downlink transmission and uplinktransmission may be executed in a cell, in parallel. Although uplinktransmission and downlink transmission are parallelly executable in asingle cell in FDD, downlink transmission and uplink transmission maynot be executed in parallel, depending on whether a UE supports fullduplex or half duplex. For example, when a UE operates as a full-duplexmode, the UE may receive downlink data and may transmit uplink data, inparallel. However, when the UE operates as a half-duplex mode, the UEmay not simultaneously execute reception of downlink data andtransmission of uplink data.

In D2D communication, when a UE operates as a full-duplex mode, the UEmay receive downlink data from another UE or a BS, and may transmituplink data to another UE or the BS, in parallel. However, when the UEoperates as a half-duplex mode, the UE may not parallelly executereception of downlink data from another UE or a BS, and transmission ofuplink data to another UE or the BS.

FIG. 2 is a conceptual diagram illustrating a structure of a radio frameaccording to an exemplary embodiment.

FIG. 2 illustrates a structure of a radio frame for Time DivisionDuplexing (FDD)-based D2D communication.

Referring to FIG. 2, a radio frame structure for the TDD may include 10subframes, like the radio frame structure of the FDD. A single subframeincludes two slots. Basically, the radio frame structures are similar.However, a predetermined subframe among subframes included in the radioframes of the TDD may be defined as a special subframe. The specialsubframe may be a time resource for switching uplink transmission anddownlink reception. The special subframe may be formed of a downlinkpart (DwPTS), a Guard Period (GP), and an uplink part (UpPTS).

In TDD, only a single carrier frequency exists, and thus, uplinktransmission and downlink transmission may be distinguished based ontime in a single cell. For example, on a single carrier frequency, a UEthat executes D2D communication, transmits uplink data to another UE ora BS in a time resource for uplink transmission and receives downlinkdata from another UE or the BS in a time resource for downlinktransmission.

FIG. 3 is a conceptual diagram illustrating D2D communication accordingto an exemplary embodiment.

D2D communication refers to a technology in which UEs directly receiveand transmit data. Hereinafter, a UE disclosed in exemplary embodimentsis assumed to support D2D communication.

When UEs located close to one another execute D2D communication in acellular system, loads on an evolved NodeB (eNodeB) may be dispersed. Inaddition, when UEs execute D2D communication, a UE transmits data arelatively short distance, and thus, transmission power consumption andtransmission latency of the UE may decrease. In addition, from theperspective of the whole system, the existing cellular-basedcommunication and the D2D communication use identical resources, andthus, frequency utilization efficiency may be improved.

The D2D communication may be classified into a communication method of aUE located within a network coverage (base station coverage) and acommunication method of a UE located outside a network coverage (basestation coverage).

Referring to FIG. 3, the communication between a first UE 310 located ina first cell and a second UE 320 located in a second cell may be D2Dcommunication between a UE included in a network coverage and a UEincluded in a network coverage. The communication between a fourth UE340 located in the first cluster and a fifth UE 350 located in the firstcluster may be D2D communication between the UEs located outside anetwork coverage. The fifth UE 350 is the cluster header, and thecluster header may operate as an independent Synchronization Source(ISS) for synchronization of an out-of coverage UE.

The D2D communication may include a discovery process that executesdiscovery for communication between UEs and a direct communicationprocess in which UEs transmit and receive control data and/or trafficdata.

The D2D communication may be used for various purposes. For example, D2Dcommunication within a network coverage and D2D communication outside anetwork coverage may be used for public safety. The D2D communicationoutside a network coverage may be used for only the public safety. D2Dcommunication in a BS coverage may be executed based on a BS. Forexample, a BS 300 may transmit D2D resource allocation information tothe first UE 310 located in the BS coverage. The D2D resource allocationinformation may include allocation information associated with a D2Dcommunication resource for D2D communication between the first UE 310and another UE (for example, a second UE 320). The first UE 310 thatreceives the D2D resource allocation information from the BS, maytransmit the D2D resource allocation information to the second UE 320outside the BS coverage. The second UE 320 may be a UE located outsidethe BS coverage, from the perspective of the BS 300 of a first cell. Thefirst UE 310 and the second UE 320 may execute D2D communication basedon the D2D resource allocation information. Particularly, the second UE320 may obtain information associated with the D2D communicationresource of the first UE 310. The second UE 320 may receive traffic dataand/or control data transmitted from the first UE 310, through aresource indicated by the information associated with the D2Dcommunication resource of the first UE 310.

In the D2D communication, a UE may transmit control data to another UE.A separate channel (for example, a Physical Uplink Control Channel(PUCCH)) for transmitting control data may not be defined in the D2Dcommunication. When the control channel is not defined in the D2Dcommunication, a UE may use various methods for transmitting controldata for D2D communication. In the D2D communication, the control datamay be expressed as Scheduling Assignment (SA) information. In the D2Dcommunication, actual traffic data (e.g., data transmitted throughshared channel, such as physical sidelink shared channel) distinguishedfrom control data, may be expressed as D2D data.

The D2D communication within network coverage may be expressed as firstmode communication, and the D2D communication outside network coveragemay be expressed as second mode communication. In the first modecommunication, a BS or a relay node schedules accurate informationassociated with resources for the D2D communication between UEs.Particularly, according to the first mode communication, a BS transmits,to a UE, resource allocation information associated with control data(or SA data) and resource allocation information associated with trafficdata (or D2D data).

According to the second mode communication, a UE may directly scheduleresources for D2D communication, based on a D2D resource pool.Particularly, in the second mode communication, resource allocationinformation for transmission of control data and resource allocationinformation associated with traffic data may be selected by a UE fromthe D2D resource pool. The D2D resource pool may be pre-configured orsemi-statically allocated.

Within the network coverage, the first mode communication or the secondmode communication may be used as a D2D communication. Outside thenetwork coverage, the second mode communication may be used as a D2Dcommunication.

A D2D communication resource for transmitting or receiving control dataor traffic data for D2D communication, may roughly include a D2D SAresource for transmitting control data and a D2D data resource fortransmitting traffic data.

The D2D data resource may be a resource used for transmitting and/orreceiving traffic data in D2D communication.

The D2D data resource may be defined based on a subframe unit in a timeaxis and based on a Resource Block (RB) unit in a frequency axis, butthis may not be limited thereto. The D2D data resource may be acandidate resource that may transmit traffic data by a D2D UE. That is,the D2D data resource may be expressed as a D2D data candidate resourceor a D2D data transmission opportunity. A UE may transmit traffic datathrough a part or the entirety of the D2D data resource. The D2D dataresource that is actually used by a UE for transmitting traffic data maybe expressed as a selected D2D data resource.

The D2D SA resource may be a resource that is used for transmittingand/or receiving control data in D2D communication. In the same manner,the D2D SA resource may be defined based on a subframe unit in a timeaxis and based on a Resource Block (RB) unit in a frequency axis, butthis may not be limited thereto. The D2D SA resource may be a candidateresource that may transmit control data by a D2D UE. That is, the D2D SAresource may be expressed as a D2D SA candidate resource or a D2D SAtransmission opportunity. The UE may transmit control data through apart of the D2D SA resource. The D2D SA resource that the UE actuallyuses for transmitting control data, may be expressed as a selected D2DSA resource.

A selected D2D data resource and a selected D2D SA resource may bedefined, respectively, by patterns on the D2D data resource and the D2DSA resource. The pattern associated with the selected D2D data resourceand/or the pattern associated with the selected D2D SA resource may beexpressed as a Resource Pattern for Transmission (RPT), andparticularly, may be expressed as a Time Resource Pattern forTransmission (T-RPT) on the time axis.

A set of D2D data resources may be expressed as a D2D data resourcepool, and a set of D2D SA resources may be expressed as a D2D SAresource pool. The D2D resource pool may be used as a concept includingthe D2D data resource pool and the D2D SA resource pool.

Hereinafter, an exemplary embodiment will disclose a method of defininga D2D data resource in a D2D data allocation period, in detail.Hereinafter, a D2D data resource may be classified into a D2D datatransmission resource used for D2D data transmission and a D2D datareception resource used for D2D data reception.

FIG. 4 is a conceptual diagram D2D communication resources according toan exemplary embodiment.

FIG. 4 discloses a D2D data transmission resource defined in a D2D dataallocation period.

Referring to FIG. 4, a D2D data allocation period 400 may be apredetermined time unit for allocating D2D data transmission resources.The D2D data allocation period 400 may be a single value defined inadvance, or may be a value selected from among a plurality of D2D dataallocation period values defined in advance. For example, a D2D dataallocation period may be 40 ms, 80 ms, 160 ms, or 320 ms When the D2Ddata allocation period 400 is executed in subframes, the D2D dataallocation period may be 40, 80, 160, or 320 subframe units.

A D2D data transmission resource (or a transmission opportunity) may bedefined based on at least one subframe unit within the D2D dataallocation period 400. The D2D data transmission resource defined basedon at least one subframe unit may be expressed using a term called aunit D2D data transmission resource 420. That is, the D2D datatransmission resource defined in the D2D allocation period may be a setof at least one unit D2D data transmission resource 420. The unit D2Ddata transmission resource 420 may be defined based on a single subframeunit, as illustrated in FIG. 4, and may be defined based on a pluralityof subframe units. Hereinafter, descriptions will be provided under anassumption of the case in which the unit D2D data transmission resource420 is configured based on a single subframe.

A single D2D data transmission unit may be transmitted on the unit D2Ddata transmission resource 420. The D2D data transmission unit may be aMAC Protocol Data Unit (PDU) in a MAC layer or a data Transport Block(TB) in a physical layer.

A Time-Resource Pattern for Transmission (T-RPT) may be defined based ona D2D data transmission unit. The T-RPT may be a resource patterndefined in a time axis for transmitting a single D2D data transmissionunit. The T-RPT may indicate a D2D data transmission resource selectedfrom a plurality of unit D2D data transmission resources, fortransmitting a single D2D data transmission unit. When a plurality ofselected D2D data transmission resources are selected, a single D2D datatransmission unit may be transmitted repeatedly a plurality of times.The T-RPT may be defined based on a basic pattern. The T-RPT and thebasic pattern will be described in detail.

Hereinafter, the number of unit D2D data transmission resourcesallocated within a D2D data allocation period may be defined as aparameter called M. The number of D2D data transmission resourcesselected from M unit data transmission resources within the D2D dataallocation period may be defined as a parameter called N.

FIG. 5 is a conceptual diagram D2D communication resources according toan exemplary embodiment.

FIG. 5 discloses a method of determining D2D data transmission resourcesbased on D2D data transmission resource bitmap.

According to an exemplary embodiment, the D2D data transmission resource420 may be allocated by taking into consideration a D2D datatransmission resource offset 440 in the D2D data allocation period 400,a D2D data transmission resource bitmap 460, and the number ofrepetitions 480 of a D2D data resource indication bitmap.

The D2D data transmission resource offset 440 may indicate theallocation location of a first D2D data transmission resource bitmap inthe D2D data allocation period. The D2D data transmission resourceoffset 440 may be a time interval corresponding to N subframes on a timeaxis. The D2D data transmission resource offset 440 may indicate astarting point of a D2D data transmission resource that is based on aD2D data transmission resource bitmap. Particularly, on subframes aftera point indicated as the D2D data transmission resource offset 440, aD2D data transmission resource that is based on the D2D datatransmission resource bitmap 460 is repeated as many as the number ofrepetitions 480 of a D2D data transmission resource bitmap.

The D2D data transmission resource bitmap 460 may be defined on asubframe unit including K subframes, in time axis. The subframe unitthat defines the D2D data transmission resource bitmap 460 may beexpressed as a bitmap subframe unit.

Bits on the D2D data transmission resource bitmap 460 correspond tosubframes included in the bitmap subframe unit, respectively, and thenumber of subframes included in the bitmap subframe unit may be thelength of the D2D data transmission resource bitmap 460. For example,when the number of subframes included in the bitmap subframe unit is K,the length of the D2D data transmission resource bitmap 460 may be K.Although K may be a predetermined value determined by taking intoconsideration a D2D data resource allocation period among multiples of 8or multiples of 10, this may not be limited thereto, and various valuesmay be used. For example, when the length of a single radio frame is 10ms, the length of the D2D data transmission resource bitmap 460 isdefined as 10, or may be indicated as a form in which it is repeated inthe D2D data allocation period 400. Alternatively, the length of the D2Ddata transmission resource bitmap 460 may be defined as 5, or may beindicated as a form in which it is repeated in the D2D data allocationperiod 400. Alternatively, the length of the D2D data transmissionresource bitmap 460 may be defined as 20, or may be indicated as a formin which it is repeated in the D2D data allocation period 400.

When the D2D data transmission resource 420 corresponds to a pluralityof subframes, bits on the D2D data transmission resource bitmap 460 maycorrespond to unit D2D data transmission resources (plurality ofsubframes) included in the bitmap subframe unit, respectively.Hereinafter, an exemplary embodiment will provide descriptions under anassumption that bits of the D2D data transmission resource bitmap 460correspond to subframes included in a bitmap subframe unit,respectively.

Values of the plurality of bits included in the D2D data transmissionresource bitmap 460 may be 0 or 1. When a bit value corresponding to apredetermined subframe of the D2D data transmission resource bitmap 460is 1, the predetermined subframe may be a D2D data transmissionresource. When a bit value corresponding to a predetermined subframe ofthe D2D data transmission resource bitmap 460 is 0, the predeterminedsubframe may be a non-D2D data transmission resource. Conversely, when abit value corresponding to a predetermined subframe on the D2D datatransmission resource bitmap 460 is 0, the predetermined subframe may bea D2D data transmission resource, and when a bit value corresponding toa predetermined subframe on the bit map is 1, the predetermined subframemay be a non-D2D data transmission resource.

In FIG. 5, the length K of the D2D data transmission resource bitmap 460is 10, and the D2D data transmission resource bitmap 460 may be‘1010010100.’ The bits of the bitmap may sequentially correspond to 10subframes, respectively, from the most significant bit to the leastsignificant bit. That is, the length of the D2D data transmissionresource bitmap 460 may be 10, and the D2D data transmission resourcebitmap 460 may indicate, as a D2D data transmission resource, 4subframes that correspond to a bit value of 1, from among the 10subframes.

The number of repetitions 480 of a D2D data transmission resource bitmapmay be the number of repetitions of a bitmap subframe unit. When thelength of the D2D data transmission resource bitmap 460 is K, the numberof repetitions R of a bitmap subframe unit on a time axis may bedetermined as 0<R≦└(P−C)/K┘. Here, P denotes a D2D data allocationperiod, and C denotes a D2D data transmission resource offset.

For example, as illustrated in FIG. 4, when the length K of the D2D datatransmission resource bitmap 460 is 10 ms, the D2D data resource offset440 is 2 ms, the D2D data resource allocation period 400 is 160 ms (or160 subframes), the number of repetitions R 480 of the D2D datatransmission resource bitmap may be a value in a range of 0<R≦15. Thatis, at most 15 repetitions may be executed. When the number ofrepetitions of the D2D data transmission resource bitmap is less than15, a D2D data transmission resource 420 based on the D2D datatransmission resource bitmap 460 may be allocated within only a fewsubframes in the D2D data resource allocation period 400.

As the D2D data allocation period P 400 becomes long, and the D2D datatransmission resource offset C 440 and the length K of the D2D datatransmission resource bitmap 460 becomes short, the number ofrepetitions 480 of the D2D data transmission resource bitmap becomeshigh. By taking into consideration the maximum value of the number ofrepetitions 480 of the D2D data transmission resource bitmap, a D2D datatransmission resource may be allocated in the D2D data allocation period400. For example, when P=320, C=0, and K=8, 0<R≦40. In this instance, asthe number of repetitions 480 of the D2D data transmission resourcebitmap, one out of 1 to 40 may be selected. Based on the selected valuecorresponding to the number of repetitions 480 of the D2D datatransmission resource bitmap, a D2D data transmission resource may beallocated in the D2D data allocation period 400.

Information associated with the D2D data allocation period 400,information associated with the D2D data transmission resource offset440, information associated with the D2D data transmission resourcebitmap 460, and information associated with the number of repetitions480 of the D2D data transmission resource bitmap may be commoninformation for UEs included in a UE set.

Information for allocating a D2D data transmission resource to anindividual UE or a UE group, may be UE-specific information of a UEgroup-specific information. The information for allocating the D2D datatransmission resource 420 to an individual UE or a UE group may beexpressed as a term called D2D data transmission resource allocationinformation.

FIG. 6 illustrates a method of determining selected D2D communicationresources according to an exemplary embodiment.

FIG. 6 discloses a method of transmitting a D2D data transmission uniton a D2D data transmission resource selected from D2D data transmissionresources that are based on a D2D data transmission resource bitmap.

M, which is the number of entire unit D2D data transmission resourcesallocated within the D2D data allocation period, may be a product of thetotal number A of repetitions of a D2D data transmission resource bitmapand the number of D2D data transmission resources M_(s) that is based ona single D2D data transmission resource bitmap.

Particularly, the total number A of repetitions of the D2D datatransmission resource bitmap may be equal to or less than a sum (A₀+A₁+. . . +A_(i)+ . . . +A_(D-1)) of the number of repetitions of a D2D datatransmission resource bitmap for each of D D2D data transmission units,which are transmitted within the D2D data allocation period. The D D2Ddata transmission units may be D2D data transmission unit 0 to D2D datatransmission unit D−1. A_(i) may indicate the number of repetitions of aD2D data transmission resource bitmap for a D2D data transmission unit i(i is an integer in a range from 0 to D−1). M_(s) is the number of D2Ddata transmission resources defined in a single D2D data transmissionresource bitmap. Therefore, the number of D2D data transmissionresources for each of the D D2D data transmission units may be A₀·M_(s),A₁·M_(s), . . . , A_(i)·M_(s), . . . , and A_(D-1)·M_(s).

For example, when K=10, M_(s)=4, and A=15, a D2D data transmissionresource bitmap (4 bits out of 10 bits correspond to ‘1’) is repeated 15times (A=15) within the D2D data resource allocation period and D2D datatransmission resources may be determined. In this instance, 60 which isa product of M_(s) and A may be the number of unit D2D data transmissionresources within the D2D data allocation period.

A D2D data transmission unit may be transmitted based on a D2D datatransmission resource bitmap-based D2D data transmission resource. Inthis instance, the D2D data transmission resources for a single D2D datatransmission unit may be determined based on at least one D2D datatransmission resource bitmap. For example, a predetermined D2D datatransmission unit may be transmitted on a one time-repeated D2D datatransmission bitmap-based D2D data transmission resource, and anotherD2D data transmission unit may be transmitted on a plurality of timesrepeated D2D data transmission resource bitmap units-based D2D datatransmission resource.

Particularly, it is assumed that the number of repetitions of the D2Ddata transmission resource bitmap is 5 (A=5), and D2D data transmissionunit 0 and D2D data transmission unit 1 are transmitted within the D2Ddata resource allocation period. Also, it is assumed that A₀ is 2, A₁ is3, and M_(s)=4. In this instance, D2D data transmission unit 0 istransmitted through D2D data transmission resource 0 that is based ontwo times-repeated D2D data transmission resource bitmaps, and D2D datatransmission unit 1 may be transmitted through D2D data transmissionresource 1 that is based on three times-repeated D2D data transmissionresource bitmaps. The number (A₀·M_(s)) of D2D data transmissionresources corresponding to D2D data transmission resource 0 is 8 and thenumber (A₁·M_(s)) of D2D data transmission resources corresponding toD2D data transmission resource 1 is 12.

D2D data transmission unit 0 may be transmitted through a selected datatransmission resource 0 out of the D2D data transmission resource 0. Inthe same manner, D2D data transmission unit 1 may be transmitted througha selected data transmission resource 1 out of D2D data transmissionresource 1.

The number of D2D data transmission resources selected for each of the DD2D data transmission units (or the number of times of transmissions ofthe D2D data transmission unit) may be expressed as L₀, L₁, . . . , . .. , and L_(D-1). For example, when L₀ is 4, D2D data transmission unit 0may be transmitted repeatedly four times on four D2D data transmissionresources selected out of D2D data transmission resources for the D2Ddata transmission unit 0.

N selected D2D data transmission resource may be a sum of L₀, L₁, . . ., . . . , and L_(D-1) (N=L₀+L₁+ . . . +L_(i)+ . . . +L_(D-1)). Forexample, L₀, L₁, . . . , L_(i), . . . , L_(D-1) may be 1, 2, 4, or 8,respectively.

That is, a single D2D data transmission unit may be transmitted on L_(i)D2D data transmission resources selected out of A_(i)·M_(s) D2D datatransmission resources.

D2D data transmission resources for transmitting a single D2D datatransmission unit and D2D data transmission resources selected out ofD2D data transmission resources for transmitting a single D2D datatransmission unit may be patternized, and the pattern is a T-RPT.

FIG. 7 is a conceptual diagram illustrating a T-RPT according to anexemplary embodiment.

The T-RPT is a pattern of a D2D data transmission resource fortransmitting a single D2D data transmission unit and a D2D datatransmission resource selected out of a D2D data transmission resource.

According to an exemplary embodiment, the T-RPT may be determined byextending a basic pattern. That is, the T-RPT may include at least onebasic pattern.

The basic pattern may indicate Y D2D data transmission resources out ofX D2D data transmission resources. That is, X is a parameter indicatingthe number of D2D data transmission resources defining the basicpattern, and Y is a parameter indicating the number of D2D datatransmission resources selected out of D2D data transmission resourcesfor defining the basic pattern.

The basic pattern may be defined based on various X and Y values.Referring to FIG. 7, T-RPT 0 for a first D2D data transmission unit(first MAC PDU in MAC layer, first data TB in physical layer) may beformed of two basic patterns based on X=4 and Y=2 (or a single basicpattern based on X=8 and Y=4), and T-RPT 1 for a second D2D datatransmission unit (second MAC PDU in MAC layer, second data TB inphysical layer) may be formed of two basic patterns based on X=4 and Y=2(a single basic pattern based on X=8 and Y=4).

For example, basic pattern 0 and basic pattern 1 may be determined basedon X=4 and Y=2. In this instance, the basic pattern may indicate two D2Ddata transmission resources selected out of 4 D2D data transmissionresources by using various combinations based on a hadamard code havinga length of 4 (or Walsh code). Alternatively, basic pattern 0 and basicpattern 1 may be determined based on X=8 and Y=4. In this instance, thebasic pattern may indicate four D2D data transmission resources selectedout of 8 D2D data transmission resources by using various combinationsbased on a hadamard code having a length of 8 (or Walsh code).

That is, the basic pattern may be determined based on X=2″(m≧2) andY=X/2. In this instance, the basic pattern may indicate Y D2D datatransmission resources selected out of X D2D data transmission resourcesby using one of the various combinations based on a hadamard code havinga length of 2′. Here, a basic pattern indication bit for indicatinginformation associated with a basic pattern that is used from amongvarious combinations for a basic pattern, may be at least m+1 bits. Whenthe number of bits allocated to the information associated with a basicpattern is limited to a predetermined number of bits (for example, 4bits or 5 bits), only a few combinations for a basic pattern out ofpossible basic patterns may be used.

According to an exemplary embodiment, the number of D2D datatransmission resources selected from a basic pattern (or the number ofrepetitions of a D2D data transmission unit) may be a multiple of 2 suchas 1, 2, 4, 8, and the like. When the number of selected D2D datatransmission resources is configured as one of the various values,flexibility of a D2D communication coverage may be secured.

The number of times of transmissions of a D2D data transmission unit maybe more flexibly applied by taking into consideration variouscommunication coverages. For example, in a scenario where many terminalsexecute D2D communication in a relatively wide communication coverage(for example, D2D communication to cover a broad coverage such as anemergency situation or the like when an ISS is distant from a basestation), the scenario may increase the number of times of transmissionsof a D2D data transmission unit even though there is overhead associatedwith D2D communication resources. Conversely, in a scenario where D2Dcommunication is possible with a relatively narrow communicationcoverage (for example, D2D communication for advertisements with respectto neighboring terminals, such as D2D communication among neighboringterminals and the like), the scenario may reduce the number of times oftransmissions of a D2D data transmission unit so as to reduce overheadassociated with D2D communication resources. Also, by taking intoconsideration Voice over Internet Protocol (VoW) and the like, D2Dcommunication may be executed based on the relatively small number oftimes of transmissions of a D2D data transmission unit.

Hereinafter, an exemplary embodiment discloses various basic patterns.

FIG. 8 is a table illustrating a basic pattern according to an exemplaryembodiment.

FIG. 8 discloses a basic pattern of X=4 and Y=2, determined based on ahadamard code having a length of 4. The basic pattern may be expressedas a term, (4, 2) basic pattern.

Referring to FIG. 8, in the table associated with a hadamard code-basedbasic pattern, ‘1’ may indicate a selected D2D data transmissionresource. Also, ‘−1’ may indicate a D2D data transmission resourcethrough which a D2D data transmission unit is not transmitted.

According to an exemplary embodiment, six (4, 2) basic patterns may bedetermined based on hadamard codes excluding a few codes that do notsatisfy X=4 and Y=2 from the hadamard codes having a length of 4. Eachof the six (4, 2) basic patterns may be indicated as (4, 2) basicpattern 0 to (4, 2) basic pattern 5.

(4, 2) basic pattern 0 to (4, 2) basic pattern 2 from among the six (4,2) basic patterns, may be defined based on the hadamard codes having alength of 4. (4, 2) basic pattern 3 to (4, 2) basic pattern 5 from amongthe six (4, 2) basic patterns, may be defined based on codes determinedby multiplying −1 and each code value of the hadamard codes having alength of 4.

At least 3 bits may be required to indicate a predetermined (4, 2) basicpattern from among the six (4, 2) basic patterns. The bits forindicating a basic pattern may be referred to as a basic patternindication bit. A single T-RPT may include at least one basic pattern.For example, one T-TRP may be configured based on one or multiple timesof repetitions of a predetermined basic pattern out of (4, 2) basicpatterns.

FIG. 9 is a table illustrating a basic pattern according to an exemplaryembodiment.

FIG. 9 discloses a basic pattern of X=8 and Y=4, determined based on ahadamard code having a length of 8. The basic pattern may be expressedas a term, (8, 4) basic pattern.

Referring to FIG. 9, fourteen (8, 4) basic patterns may be determinedbased on hadamard codes excluding a few codes that do not satisfy X=8and Y=4 from the hadamard codes having a length of 8. Each of thefourteen (8, 4) basic patterns may be indicated as (8, 4) basic pattern0 to (8, 4) basic pattern 13.

(8, 4) basic pattern 0 to (8, 4) basic pattern 6 from among the fourteen(8, 4) basic patterns, may be defined based on the hadamard codes havinga length of 8. (8, 4) basic pattern 7 to (8, 4) basic pattern 13 fromamong the fourteen (8, 4) basic patterns, may be defined based on codesdetermined by multiplying −1 and each code value of the hadamard codeshaving a length of 8.

A basic pattern indication bit for indicating fourteen basic patternsmay be at least 4 bits. A single T-RPT may include at least one basicpattern. For example, one T-TRP may be configured based on one ormultiple times of repetitions of a predetermined basic pattern out of(8, 4) basic patterns.

FIG. 10 is a table illustrating a basic pattern according to anexemplary embodiment.

FIG. 10 discloses a basic pattern of X=16 and Y=8, determined based on ahadamard code having a length of 16. The basic pattern may be expressedas a term, (16, 8) basic pattern.

Referring to FIG. 10, 30 (16, 8) basic patterns may be determined basedon hadamard codes excluding a few codes that do not satisfy X=16 and Y=8from the hadamard codes having a length of 16. 16 basic patterns may bedefined by taking into consideration a basic pattern indication bit of 4bits. (16, 8) basic pattern 0 to (16, 8) basic pattern 7 from among thesixteen (16, 8) basic patterns, may be defined based on the hadamardcodes having a length of 16. For example, (16, 8) basic pattern 0 to(16, 8) basic pattern 7 may be determined based on a total of 8 defaulthadamard codes from a second hadamard code, excluding a first hadamardcode formed of only ‘+1’ from the default hadamard codes having a lengthof 16. Among sixteen (16, 8) basic patterns, the remaining (16, 8) basicpattern 8 to (16, 8) basic pattern 15 may be determined based on codesdetermined by multiplying −1 and each code value of the hadamard codescorresponding to (16, 8) basic pattern 0 to (16, 8) basic pattern 7.

In the same manner, a single T-RPT may include at least one basicpattern. For example, one T-TRP may be configured based on one ormultiple times of repetitions of a predetermined basic pattern out of(16, 8) basic patterns.

A basic pattern determined based on a hadamard code disclosed in FIGS. 8to 10, may be generalized and may be expressed as follows.

A basic pattern of X=2^(m) and Y=X/2, determined based on a hadamardcode having a length of 2^(m), may be generated. The basic pattern maybe expressed as a term, (2^(m), 2^(m−1)) basic pattern.

The number of possible basic patterns for a T-RPT, which is based on ahadamard code having a length of 2^(m), may be determined as follows.

In the case of a hadamard code having a length of 2^(m), 2^(m) hadamardcodes may exist. When a first hadamard code formed of code values ofonly ‘1’ is excluded from 2^(m) hadamard codes, 2^(m−1) hadamard codesmay be used for determining a basic pattern. Also, a code obtained bymultiplying −1 and a hadamard code may be used for determining a basicpattern.

Therefore, when a hadamard code having a length of 2^(m) is used, thenumber of possible basic patterns for a T-RPT may be2·(2^(m−1))=2^(m+1)−2. That is, when a hadamard code having a length of2^(m) is used, the number of possible basic patterns for a T-RPT may be2^(m+1)−2.

For example, when a hadamard code having a length of 4 with m=2 is used,the number of basic patterns may be 6, when a hadamard code having alength of 8 with m=3 is used, the number of basic patterns may be 14,when a hadamard code having a length of 16 with m=4 is used, the numberof basic patterns may be 30, when a hadamard code having a length of 32with m=5 is used, the number of basic patterns may be 62, and when ahadamard code having a length of 64 with m=6 is used, the number ofbasic patterns may be 126.

A basic pattern indication bit for indicating one of the plurality ofbasic patterns that are based on a hadamard code having a length of2^(m), may be at least m+1 bit. When the number of bits for a basicpattern indication bit is limited, only a few basic patterns may be usedfrom among possible basic patterns that are based on a hadamard codehaving a length of 2^(m). For example, when the basic pattern indicationbit is limited to 4 bits, basic patterns based on a maximum of 16hadamard codes may be used. When the basic pattern indication bit islimited to 5 bits, basic patterns based on a maximum of 32 hadamardcodes may be used.

When the basic pattern indication bit is limited to 4 bits, six (4, 2)basic patterns and fourteen (8, 4) basic patterns may be indicated basedon the basic pattern indication bit. Also, when the basic patternindication bit is limited to 4 bits, sixteen (16, 8) basic patterns outof 30 possible (16, 8) basic patterns disclosed in FIG. 10 may beindicated.

The number M of unit D2D data transmission resources within a D2D dataresource allocation period and the number N of selected D2D datatransmission resources are fixed, D2D data transmission resources andselected D2D data transmission resources may be allocated based on atleast one basic pattern defined in advance, as described in FIGS. 8 to10. For example, when M=32 and N=16, a basic pattern may be configuredbased on X=8 and Y=4.

However, M may have full flexibility using a bitmap or the like. N mayalso be variable based on the number of repetitions of a single D2D datatransmission unit and the number of different D2D data transmissionresources transmitted within a D2D data resource allocation period.

When M and N are variable, and D2D data transmission resources andselected D2D data transmission resources are allocated based on apredetermined basic pattern, the use of D2D communication resource maybe inefficient. Therefore, a basic pattern may need to be configuredvariably. When the basic pattern is variable, overhead of a signalingfor signaling a changed basic pattern may occur.

Therefore, there is desire for a method for supporting variable M or Nwithout overhead for signaling a changed pattern.

Hereinafter, in an exemplary embodiment, (X, Y) that is increased byrepetitions of a basic pattern may be expressed as (Xrep, Yrep), (X, Y)that is decreased by using a part of a basic pattern may be expressed as(Xred, Yred), and (X, Y) of a finally changed pattern may be expressedas a parameter (Xnew, Ynew).

The term, D2D data transmission resources (Xrep) and selected D2D datatransmission resources (Yrep), may be used for indicating D2D datatransmission resources and selected D2D data transmission resources,which are extended by repeating a basic pattern.

The term, D2D data transmission resources (Xred) and selected D2D datatransmission resources (Yred), may be used for indicating D2D datatransmission resources and selected D2D data transmission resources,which are reduced by reduction of a basic pattern.

The term, D2D data transmission resources (Xnew) and selected D2D datatransmission resources (Ynew), may be used for indicating D2D datatransmission resources and selected D2D data transmission resources,which are indicated based on a changed pattern.

Hereinafter, a changed pattern of a basic pattern for supporting avariable M and/or N is disclosed. The case in which L_(i) D2D datatransmission resources out of A_(i)·M_(s) D2D data transmissionresources are actually used for transmitting a single D2D datatransmission unit, may be considered.

A changed pattern may be determined, by excluding the case ofX>A_(i)·M_(s). A basic pattern may be determined to enable X to be lessthan or equal to A₁·M_(s).

FIG. 11 is a conceptual diagram illustrating a method of generating achanged pattern, based on a basic patter according to an exemplaryembodiment.

FIG. 11 discloses a changed pattern that is generated based on a basicpattern, for supporting variable M and/or N, when X=A_(i)·M_(s).

When X=Ai·Ms, a changed pattern may be determined by comparing sizesbetween Y and L_(i). For example, the case X=8 and A_(i)·M_(s)=8 may beassumed.

Y>L _(i)  1

The upper diagram of FIG. 11 discloses a method of generating a changedpattern when Y>Li.

When Y>L_(i), only L_(i) selected D2D data transmission resources whichare temporally earlier may be determined as selected D2D datatransmission resources (Ynew) of a changed pattern. Actual traffictransmission may not be executed in the remaining Y−L_(i) selected D2Ddata transmission resources.

Particularly, when Y=4 and L_(i)=2, only first two selected D2D datatransmission resources of the basic pattern may be determined asselected D2D data transmission resources (Ynew) of the changed pattern.Data may not be transmitted in the remaining two selected D2D datatransmission resources.

Y=L _(i)  2

A UE may not determine a changed pattern separately, and may transmitdata based on the basic pattern.

For example, when Y=4 and L_(i)=4, the UE may transmit data throughselected D2D data transmission resources that are based on the basicpattern set in advance.

Y<L _(i)  3

The lower diagram of FIG. 11 discloses a method of generating a changedpattern when Y<L_(i).

X-Y D2D data transmission resources remaining after excluding Y selectedD2D data transmission resources from X D2D data transmission resourcesmay be determined as selected D2D data transmission resources (Ynew) ofa changed pattern.

Particularly, at least one D2D data transmission resource out of the X-Yremaining D2D data transmission resources may be determined as aselected D2D data transmission resource (Ynew) of a changed pattern.Remaining D2D data transmission resources that are temporally earlierout of the X-Y remaining D2D data transmission resources may bepreferentially determined as selected D2D data transmission resources(Ynew) of the changed pattern. In the changed pattern, the number ofselected D2D data transmission resources (Ynew) selected based on theaddition of selected D2D data transmission resources, as describedabove, may be L_(i).

For example, the case X=4 and L=8 may be assumed. A (8, 4) basic patternforming a T-RPT may indicate four selected D2D data transmissionresources out of 8 D2D data transmission resources. In this instance, aUE may transmit data based on a changed pattern in which all of the 8D2D data transmission resources of the basic pattern are set as selectedD2D data transmission resources (Ynew).

FIG. 12 is a conceptual diagram illustrating a method of generating achanged pattern based on a basic pattern according to an exemplaryembodiment.

FIG. 12 discloses a changed pattern that is generated based on a basicpattern for supporting variable M and/or N, when X<A_(i)·M_(s).

When X<A_(i)·M_(s), a changed pattern may be determined by comparingsizes between Y and L_(i).

When X<A_(i)·M_(s), a basic pattern may be repeated as many as┌(A_(i)·M_(s))/X┐ times. A length Xrep of ┌(A_(i)·M_(s))/X┐times-repeated basic patterns may be greater than or equal toA_(i)·M_(s).

For example, when X=8 and A_(i)·M_(s)=16, the basic pattern may berepeated two times. As another example, when X=8 and A_(i)·M_(s)=20, thebasic pattern may be repeated three times. By repeating the basicpattern three times, eight D2D data transmission resources may beextended to 24 D2D data transmission resources (Xrep). The changedpattern may be defined in 20 D2D data transmission resources (Xnew)which are temporally earlier out of the 24 D2D data transmissionresources (Xrep). When the basic pattern is repeated, the selected D2Ddata transmission resources may be extended to selected D2D datatransmission resources (rep).

For example, the case of X=8, Y=4, and A_(i)·M_(s)=16 may be assumed.When a changed pattern is configured by repeating the basic pattern twotimes, Yrep may be 8. As another example, when X=8, Y=4, andA_(i)·M_(s)=20, the basic pattern may be repeated three times. Anapplication range of three-times repeated basic patterns may be extendedto 24 (=Xrep) D2D data transmission resources (Xrep). The changedpattern may be defined in only first 20 D2D data transmission resources(Xnew) out of the 24 D2D data transmission resources. The selected D2Ddata transmission resources may also be extended to selected D2D datatransmission resources (Yrep), by repeating the basic pattern. Yrep is avalue greater than Y.

The selected D2D data transmission resources (Ynew) of the changedpattern may be determined by comparing the size between Yrep determinedbased on repetition of the basic pattern and L_(i).

Yrep>L _(i)  1

FIG. 12 illustrates a method of determining selected D2D datatransmission resources on a changed pattern when Yrep>L_(i).

When Yrep>L_(i), selected D2D data transmission resources (Ynew) may beset in only L_(i) selected D2D data transmission resources that aretemporally earlier from among selected D2D data transmission resources(Yrep). Actual data transmission may not be executed in the Yrep-Lremaining selected D2D data transmission resources. That is, only a fewof selected D2D data transmission resources out of the D2D datatransmission resources selected to satisfy Ynew=L_(i), may be used fordata transmission.

For example, when Yrep=8 and L_(i)=4, only four selected D2D datatransmission resources that are temporally earlier from among eightselected D2D data transmission resources (Yrep) may be determined asselected D2D data transmission resources (Ynew). Data may not betransmitted in the four remaining selected D2D data transmissionresources. That is, a UE may disregard the four remaining selected D2Ddata transmission resources, and may not transmit data.

Yrep=L _(i)  2

When Yrep=Li, changing a pattern may not be separately needed. The UEmay transmit data through the selected D2D data transmission resources(Yrep).

Yrep<L _(i)  3

The lower diagram of FIG. 12 illustrates a method of determiningselected D2D data transmission resources (Ynew) of a changed patternwhen Yrep<Li.

In addition to the selected D2D data transmission resources (Yrep), atleast one of the D2D data transmission resources remaining afterexcluding the selected D2D data transmission resources (Yrep) may beadditionally determined to be selected D2D data transmission resources(Ynew).

Particularly, at least one D2D data transmission resource out of theXnew-Yrep remaining D2D data transmission resources may be additionallydetermined to be selected D2D data transmission resources (Ynew).Remaining D2D data transmission resources that are temporally earliermay be determined to be selected D2D data transmission resources (Ynew).Based on the additional determination, the number of selected D2D datatransmission resources (Ynew) of the changed pattern may be L_(i).

For example, when Xnew=20, Ynew=8, and L_(i)=16, a UE may additionallydetermine eight D2D data transmission resources that are temporallyearlier as the selected data transmission resources (Ynew). That is,selected D2D data transmission resources (Yrep) and eight D2D datatransmission resources that are different from the selected D2D datatransmission resources may be set to be the selected D2D datatransmission resources (Ynew).

Hereinafter, a method of generating a changed pattern based on a basicpattern with X=4 and Y=2

Table 1 provided below shows a (4, 2) basic pattern based on Hadamardcode.

TABLE 1 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit D2D data D2Ddata D2D data D2D data transmission transmission transmissiontransmission resource resource resource resource (4, 2) +1 −1 +1 −1basic pattern 0 (4, 2) +1 +1 −1 −1 basic pattern 1 (4, 2) +1 −1 −1 +1basic pattern 2 (4, 2) −1 +1 −1 +1 basic pattern 3 (4, 2) −1 −1 +1 +1basic pattern 4 (4, 2) −1 +1 +1 −1 basic pattern 5

(4, 2) basic patterns of Table 1 are identical to (4, 2) basic patternsdisclosed in FIG. 8.

In this instance, the following cases of L_(i) will be considered. Inthis instance, A_(i)·M_(s) may be a multiple of 4.

L _(i)=1(in this instance, A _(i) ·M _(s)=4)  1

According to the above mentioned method, (Xnew, Ynew)=(4,1) may begenerated from (X, Y)=(4, 2). That is, except for a first selected D2Ddata transmission resource in each (4, 2) basic pattern of Table 1, theremaining D2D data transmission resources may not be the selected D2Ddata transmission resource, irrespective of a code value of the (4, 2)basic pattern. This may be expressed by Table 2.

Alternatively, Table 3 may be used, in which a pattern of first two unitD2D data transmission resources is identical to (2, 1) pattern. That is,according to Table 3, with respect to four unit D2D data transmissionresources (A_(i)·M_(s)=4), the (2, 1) pattern of Table 4 may be appliedto first two unit D2D data transmission resources, and D2D data is nottransmitted through the remaining two unit D2D transmission resources.

TABLE 2 1^(st) unit 2^(nd) unit 3^(th) unit 4^(th) unit D2D data D2Ddata D2D data D2D data transmission transmission transmissiontransmission resource resource resource resource (4, 1) +1 −1 −1 −1basic pattern 0 (4, 1) +1 −1 −1 −1 basic pattern 1 (4, 1) +1 −1 −1 −1basic pattern 2 (4, 1) −1 +1 −1 −1 basic pattern 3 (4, 1) −1 −1 +1 −1basic pattern 4 (4, 1) −1 +1 −1 −1 basic pattern 5

TABLE 3 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit D2D data D2Ddata D2D data D2D data transmission transmission transmissiontransmission resource resource resource resource (4, 1) +1 −1 −1 −1basic pattern 0 (4, 1) −1 +1 −1 −1 basic pattern 1

TABLE 4 1^(st) unit D2D data 2^(nd) unit D2D data transmissiontransmission resource resource (2, 1) +1 −1 basic pattern 0 (2, 1) −1 +1basic pattern 1

L _(i)=2(in this instance, A _(i) ·M _(s)=4)  2

According to the above mentioned method, (Xnew, Ynew)=(4, 2) may begenerated from (X, Y)=(4, 2). That is, Table 1 may be applied, as it is,with respect to four unit D2D data transmission resources(A_(i)·M_(s)=4).

L _(i)=4(in this instance, A _(i) ·M _(s)=8)  3

According to the above mentioned method, (Xnew, Ynew)=(8, 4) may begenerated from (X, Y)=(4, 2). That is, (Xnew, Ynew)=(8, 4) may begenerated from (Xrep, Yrep)=(8,4), which is obtained by repeating (X,Y)=(4, 2) two times. That is, with respect to eight unit D2D datatransmission resources (A_(i)·M_(s)=8), Table 1 may be applied as it is,with respect to first four unit D2D data transmission resources, andTable 1 may be applied repeatedly with respect to the remaining fourunit D2D data transmission resources.

L _(i)=8(in this instance, A _(i) ·M _(s)=16)  4

According to the above mentioned method, (Xnew, Ynew)=(16, 8) may begenerated from (X, Y)=(4, 2). That is, (Xnew, Ynew)=(16, 8) may begenerated from (Xrep, Yrep)=(16, 8), which is obtained by repeating (X,Y)=(4, 2) four times. That is, with respect to 16 unit D2D datatransmission resources (A_(i)·M_(s)=16), Table 1 may be applied as it iswith respect to first four unit D2D data transmission resources, Table 1is repeatedly applied with respect to subsequent four unit D2D datatransmission resources, Table 1 is repeatedly applied with respect tosubsequent four unit D2D data transmission resources, and Table 1 isrepeatedly applied with respect to the last four unit D2D datatransmission resources.

Hereinafter, a method of generating a changed pattern based on a basicpattern with X=8 and Y=4, will be described.

Table 5 provided below shows (8, 4) basic pattern based on Hadamardcode.

TABLE 5 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit 5^(th) unit6^(th) unit 7^(th) unit 8^(th) unit D2D data D2D data D2D data D2D dataD2D data D2D data D2D data D2D data transmission transmissiontransmission transmission transmission transmission transmissiontransmission resource resource resource resource resource resourceresource resource (8, 4) +1 −1 +1 −1 +1 −1 +1 −1 basic pattern 0 (8, 4)+1 +1 −1 −1 +1 +1 −1 −1 basic pattern 1 (8, 4) +1 −1 −1 +1 +1 −1 −1 +1basic pattern 2 (8, 4) +1 +1 +1 +1 −1 −1 −1 −1 basic pattern 3 (8, 4) +1−1 +1 −1 −1 +1 −1 +1 basic pattern 4 (8, 4) +1 +1 −1 −1 −1 −1 +1 +1basic pattern 5 (8, 4) +1 −1 −1 +1 −1 +1 +1 −1 basic pattern 6 (8, 4) −1+1 −1 +1 −1 +1 −1 +1 basic pattern 7 (8, 4) −1 −1 +1 +1 −1 −1 +1 +1basic pattern 8 (8, 4) −1 +1 +1 −1 −1 +1 +1 −1 basic pattern 9 (8, 4) −1−1 −1 −1 +1 +1 +1 +1 basic pattern 10 (8, 4) −1 +1 −1 +1 +1 −1 +1 −1basic pattern 11 (8, 4) −1 −1 +1 +1 +1 +1 −1 −1 basic pattern 12 (8, 4)−1 +1 +1 −1 +1 −1 −1 +1 basic pattern 13

(8, 4) basic patterns of Table 5 are identical to (8, 4) basic patternsdisclosed in FIG. 9.

In this instance, the following cases of L_(i) will be considered. Inthis instance, A_(i)·M_(s) may be a multiple of 8.

L _(i)=1(in this instance, A _(i) ·M _(s)=8)  1

According to the above mentioned method, (Xnew, Ynew)=(8, 1) may begenerated from (X, Y)=(8, 4). That is, except for a first selected D2Ddata transmission resource in each (8, 4) basic pattern of Table 5, theremaining D2D data transmission resources may not be the selected D2Ddata transmission resource, irrespective of a code value of (8, 4) basicpattern. This may be expressed by Table 6.

Alternatively, Table 7 may be used, in which a pattern of first two unitD2D data transmission resources is identical to (2, 1) pattern. That is,according to Table 7, with respect to eight unit D2D data transmissionresources (A_(i)·M_(s)=8), the (2, 1) pattern of Table 4 may be appliedto first two unit D2D data transmission resources, and D2D data is nottransmitted through the six remaining unit D2D transmission resources.

TABLE 6 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit 5^(th) unit6^(th) unit 7^(th) unit 8^(th) unit D2D data D2D data D2D data D2D dataD2D data D2D data D2D data D2D data transmission transmissiontransmission transmission transmission transmission transmissiontransmission resource resource resource resource resource resourceresource resource (8, 1) +1 −1 −1 −1 −1 −1 −1 −1 basic pattern 0 (8, 1)+1 −1 −1 −1 −1 −1 −1 −1 basic pattern 1 (8, 1) +1 −1 −1 −1 −1 −1 −1 −1basic pattern 2 (8, 1) +1 −1 −1 −1 −1 −1 −1 −1 basic pattern 3 (8, 1) +1−1 −1 −1 −1 −1 −1 −1 basic pattern 4 (8, 1) +1 −1 −1 −1 −1 −1 −1 −1basic pattern 5 (8, 1) +1 −1 −1 −1 −1 −1 −1 −1 basic pattern 6 (8, 1) −1+1 −1 −1 −1 −1 −1 −1 basic pattern 7 (8, 1) −1 −1 +1 −1 −1 −1 −1 −1basic pattern 8 (8, 1) −1 +1 −1 −1 −1 −1 −1 −1 basic pattern 9 (8, 1) −1−1 −1 −1 +1 −1 −1 −1 basic pattern 10 (8, 1) −1 +1 −1 −1 −1 −1 −1 −1basic pattern 11 (8, 1) −1 −1 +1 −1 −1 −1 −1 −1 basic pattern 12 (8, 1)−1 +1 −1 −1 −1 −1 −1 −1 basic pattern 13

TABLE 7 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit 5^(th) unit6^(th) unit 7^(th) unit 8^(th) unit D2D data D2D data D2D data D2D dataD2D data D2D data D2D data D2D data transmission transmissiontransmission transmission transmission transmission transmissiontransmission resource resource resource resource resource resourceresource resource (8, 1) +1 −1 −1 −1 −1 −1 −1 −1 basic pattern 0 (8, 1)−1 +1 −1 −1 −1 −1 −1 −1 basic pattern 1

L _(i)=2(in this instance, A _(i) ·M _(s)=8)  2

According to the above mentioned method, (Xnew, Ynew)=(8, 2) may begenerated from (X, Y)=(8, 4). That is, the remaining D2D datatransmission resources, excluding first two selected D2D datatransmission resources in each (8, 4) basic pattern of Table 5, may notbe the selected D2D data transmission resources, irrespective of a codevalue of the (8, 4) basic pattern. This may be expressed by Table 8.

Alternatively, Table 9 may be used, in which a pattern of first fourunit D2D data transmission resources is identical to (4, 2) pattern.That is, according to Table 9, with respect to eight unit D2D datatransmission resources (A_(i)·M_(s)=8), the (4, 2) pattern of Table 1may be applied to first four unit D2D data transmission resources, andD2D data is not transmitted through the four remaining unit D2Dtransmission resources.

TABLE 8 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit 5^(th) unit6^(th) unit 7^(th) unit 8^(th) unit D2D data D2D data D2D data D2D dataD2D data D2D data D2D data D2D data transmission transmissiontransmission transmission transmission transmission transmissiontransmission resource resource resource resource resource resourceresource resource (8, 2) +1 −1 +1 −1 −1 −1 −1 −1 basic pattern 0 (8, 2)+1 +1 −1 −1 −1 −1 −1 −1 basic pattern 1 (8, 2) +1 −1 −1 +1 −1 −1 −1 −1basic pattern 2 (8, 2) +1 +1 −1 −1 −1 −1 −1 −1 basic pattern 3 (8, 2) +1−1 +1 −1 −1 −1 −1 −1 basic pattern 4 (8, 2) +1 +1 −1 −1 −1 −1 −1 −1basic pattern 5 (8, 2) +1 −1 −1 +1 −1 −1 −1 −1 basic pattern 6 (8, 2) −1+1 −1 +1 −1 −1 −1 −1 basic pattern 7 (8, 2) −1 −1 +1 +1 −1 −1 −1 −1basic pattern 8 (8, 2) −1 +1 +1 −1 −1 −1 −1 −1 basic pattern 9 (8, 2) −1−1 −1 −1 +1 +1 −1 −1 basic pattern 10 (8, 2) −1 +1 −1 +1 −1 −1 −1 −1basic pattern 11 (8, 2) −1 −1 +1 +1 −1 −1 −1 −1 basic pattern 12 (8, 2)−1 +1 +1 −1 −1 −1 −1 −1 basic pattern 13

TABLE 9 1^(st) unit 2^(nd) unit 3^(rd) unit 4^(th) unit 5^(th) unit6^(th) unit 7^(th) unit 8^(th) unit D2D data D2D data D2D data D2D dataD2D data D2D data D2D data D2D data transmission transmissiontransmission transmission transmission transmission transmissiontransmission resource resource resource resource resource resourceresource resource (8, 2) +1 −1 +1 −1 −1 −1 −1 −1 basic pattern 0 (8, 2)+1 +1 −1 −1 −1 −1 −1 −1 basic pattern 1 (8, 2) +1 −1 −1 +1 −1 −1 −1 −1basic pattern 2 (8, 2) −1 +1 −1 +1 −1 −1 −1 −1 basic pattern 3 (8, 2) −1−1 +1 +1 −1 −1 −1 −1 basic pattern 4 (8, 2) −1 +1 +1 −1 −1 −1 −1 −1basic pattern 5

L _(i)=4(in this instance, A _(i) ·M _(s)=8)  3

According to the above mentioned method, (Xnew, Ynew)=(8, 4) may begenerated from (X, Y)=(8, 4). That is, Table 5 may be applied, as it is,with respect to eight unit D2D data transmission resources(A_(i)·M_(s)=8).

L _(i)=8(in this instance, A _(i) ·M _(s)=16)  4

According to the above mentioned method, (Xnew, Ynew)=(16, 8) may begenerated from (X, Y)=(8, 4). That is, (Xnew, Ynew)=(16, 8) may begenerated from (Xrep, Yrep)=(16.8), which is obtained by repeating (X,Y)=(8, 4) two times. That is, with respect to 16 unit D2D datatransmission resources (A_(i)·M_(s)=16), Table 5 may be applied as itis, with respect to first eight unit D2D data transmission resources,and Table 5 may be applied repeatedly with respect to the eightremaining unit D2D data transmission resources.

FIG. 13 is a conceptual diagram illustrating a method of generating achanged pattern based on a basic pattern according to an exemplaryembodiment.

As described above, it is assumed that the case in which L_(i) selectedD2D data transmission resources out of A_(i)·M_(s) D2D data transmissionresources are used with respect to a single D2D data transmission unit.Hereinafter, a method of generating a changed pattern when X is greaterthan A_(i)·M_(s), will be described.

Referring to FIG. 13, the case of X>A_(i)·M_(s) will be described. Achanged pattern may be determined based on A_(i)·M_(s) D2D datatransmission resources, which are temporally earlier from among D2D datatransmission resources.

For example, when A_(i)·M_(s)=10, a basic pattern with X=16 may beapplied. In this instance, the changed pattern may be determined basedon only 10 D2D data transmission resources that are temporally earlierout of the D2D data transmission resources of the basic pattern.

When X is decreased to Xred, Y may be decreased to Yred.

For example, when X=16, Y=8, and A_(i)·M_(s)=10, first 10 D2D datatransmission resources out of 16 D2D data transmission resources of thebasic pattern may be determined as D2D data transmission resources(Xred). The number of selected D2D data transmission resources (Yred)may be decreased to 4, 5, or 6.

Yred>L _(i)  1

Only L_(i) selected D2D data transmission resources that are temporallyearlier from among the selected D2D data transmission resources (Yrep)may be determined as D2D data transmission resources (Ynew).

For example, when Yred is 4 and L_(i) is 2, two D2D data transmissionresource that are temporally earlier out of 4 D2D data transmissionresources corresponding to Yred may be determined as the selected D2Ddata transmission resources (Ynew). Traffic data may be transmitted onlythrough the selected D2D data transmission resources (Ynew). Trafficdata may not be transmitted in the two remaining selected D2D datatransmission resources.

Yred=L _(i)  2

Traffic data may be transmitted through the selected D2D datatransmission resources (Yred).

For example, when Yred=4 and L=4, traffic data may be transmitted on theselected D2D data transmission resources, without separately generatinga separate changed pattern.

Yred<L _(i)  3

In addition to selected D2D data transmission resources (Yred), L-YredD2D data transmission resources that are temporally earlier out of D2Ddata transmission resources remaining after excluding the selected D2Ddata transmission resources (Yred) from the D2D data transmissionresources (Xred) may be additionally set as the selected D2D datatransmission resources (Ynew).

For example, when Xred=10, Yred=4, and L=8, 4 D2D data transmissionresources that are temporally earlier out of 6 D2D data transmissionresources remaining after excluding the selected D2D data transmissionresources (Yred) from the D2D data transmission resources (Xred), may beadditionally set as the selected D2D data transmission resources (Ynew).

A basic pattern for a T-RPT may be determined variously. As describedabove, when a hadamard code having a length of 4 is used, the number ofpossible basic patterns for a T-RPT is 6. When a hadamard code having alength of 8 is used, the number of possible basic patterns for a T-RPTis 14. When a hadamard code having a length of 16 is used, the number ofpossible basic patterns for a T-RPT is 30. When a hadamard code having alength of 32 is used, the number of possible basic patterns for a T-RPTis 62. When a hadamard code having a length of 64 is used, the number ofpossible basic patterns for a T-RPT is 126.

FIG. 14 is a flowchart illustrating an operation of transmitting trafficdata of a user equipment according to an exemplary embodiment.

Referring to FIG. 14, a D2D data transmission resource is determined inoperation S1400.

For example, a UE may receive cell-specific information for D2Dcommunication (for example, information associated with a D2D dataallocation period, information associated with a D2D data transmissionresource offset, information associated with a D2D data transmissionresource bitmap, and information associated with the number ofrepetitions of a D2D data transmission resource bitmap) and UE-specificinformation for D2D communication (for example, D2D data transmissionresource allocation information), through various methods (SIB, PD2DSCH,RRC, D2D SA resources or the like). The UE may determine a D2D datatransmission resource based on cell-specific information for D2Dcommunication and UE-specific information (UE group-specificinformation) for D2D communication.

The UE receives D2D communication resource information for transmittinga single D2D data transmission unit in operation S1420.

The UE may receive information associated with the number A_(i) ofrepetitions of a D2D data transmission resource bitmap for a single D2Ddata transmission unit, information associated with the number M_(s) ofD2D data transmission resources that are based on a single D2D datatransmission resource bitmap, and information associated with the numberL_(i) of selected D2D data transmission resources for a single D2D datatransmission unit.

The UE transmits traffic data through D2D data transmission resourcesselected based on a basic pattern or a pattern modified from the basicpattern, in operation S1440.

As disclosed in FIGS. 11 to 13, whether the basic pattern is modifiedmay be determined by comparing sizes between X (Xrep or Xred) andA_(i)·M_(s), and sizes between Y (Yrep or Yred) and L_(i).

The UE may transmit traffic data based on the basic pattern whenmodification of the basic pattern is not needed, and may transmittraffic data based on a changed pattern when the modification is needed.

FIG. 15 is a block diagram illustrating a base station (BS) and a userequipment (UE) according to an exemplary embodiment.

Referring to FIG. 15, a BS may include a D2D communication resourcedetermining unit 1500, a D2D communication resource informationgenerating unit 1510, a communication unit 1520, and a processor 1530.

The UE may include a pattern determining unit 1540, a communication unit1550, and a processor 1560. The component elements of the UE and the BSdisclosed in FIG. 15 are configured for illustrative purposes, and asingle component element may be embodied as a plurality of componentelements or a plurality of component elements may be embodied as asingle component element.

The component elements of the UE and the BS may be embodied forexecuting the operations of the BS and the UE, which have been describedin FIGS. 4 to 14. For example, the component elements of the BS and theUE may execute the following operations.

The D2D communication resource determining unit 1500 may determine thenumber of D2D data transmission resources and the number of selected D2Ddata transmission resources, for transmitting a single D2D datatransmission unit.

The D2D communication resource information generating unit 1510 of theBS may be embodied to generate information associated with the number ofD2D data transmission resources and the number of selected D2D datatransmission resources, for transmitting a single D2D data transmissionunit, which are determined by the D2D communication resource determiningunit 1500.

The communication unit 1520 of the BS may be embodied to transmit, tothe UE, the information associated with the number of D2D datatransmission resources and the number of selected D2D data transmissionresources, for transmitting a single D2D data transmission unit.

The processor 1530 of the BS may be embodied to control the operationsof the D2D communication resource determining unit 1500, the D2Dcommunication resource information generating unit 1510, and thecommunication unit 1520.

The communication unit 1550 of the UE may receive, from thecommunication unit 1520 of the BS, the information associated with thenumber of D2D data transmission resources and the number of selected D2Ddata transmission resources, for transmitting a single D2D datatransmission unit.

The pattern determining unit 1540 may determine a pattern fortransmitting a single D2D data transmission unit, based on theinformation associated with the number of D2D data transmissionresources and the number of selected D2D data transmission resources fortransmitting a single D2D data transmission unit, which is received fromthe communication unit 1520 of the BS. As disclosed in FIGS. 11 to 13,the pattern determining unit 1540 may determine a basic pattern or achanged pattern modified from the basic pattern for transmitting trafficdata, by comparing sizes between X (Xrep or Xred) and A_(i)·M_(s), andsizes between Y (Yrep or Yred) and L_(i).

The processor 1560 of the UE may be embodied to control the operationsof the pattern determining unit 1540 and the communication unit 1550.

According to an exemplary embodiment, the pattern determining unit 1540may be configured in one or more processors, e.g., the processor 1560.Software features of the pattern determining unit 1540 may be stored ina memory and may be executed by the one or more processors. Thecommunication unit 1550 may be a wireless transceiver or the UEseparately include a wireless transceiver.

The wireless transceiver may receive configuration informationassociated with a D2D data transmission resource, the configurationinformation including information of a D2D data allocation period andbeing transmitted from an evolved NodeB (eNB). The one or moreprocessors may determine a D2D data transmission resource in each D2Ddata allocation period, the D2D data transmission resource including apool of subframes, and select D2D data transmission subframes from amongthe pool of subframes based on a changed pattern, the changed patternbeing derived from a basic pattern. The wireless transceiver transmits,from the UE to another UE, D2D data based on the selected D2D datatransmission subframes.

When the number of subframes in the pool of subframes is greater than alength of the basic pattern, the one or more processors may beconfigured to determine the changed pattern by repeating the basicpattern. A length of the changed pattern may correspond to the number ofsubframes in the pool of subframes.

The changed pattern may include a partial portion of the basic patternat an end of the changed pattern without having the remaining portion ofthe basic pattern. In the basic pattern, the partial portion of thebasic pattern precedes the remaining portion of the basic pattern.

The one or more processors may be configured to determine (R mod X),wherein R corresponds to the number of subframes in the pool ofsubframes and X corresponds to a length of the basic pattern, where Rand X are natural numbers. The changed pattern may include a first partand a second part, the first part of the changed pattern including atleast one repetition of the basic pattern, and a length of the secondpart of the changed pattern may correspond to (R mod X).

When the number of subframes in the pool of subframes is less than alength of the basic pattern, the one or more processors may beconfigured to determine the changed pattern based on a value of (R modX), wherein R corresponds to the number of subframes in the pool ofsubframes and X corresponds to a length of the basic pattern, where Rand X are natural numbers. A length of the changed pattern maycorrespond to the number of subframes in the pool of subframes.

The changed pattern may consist of a first part of the basic pattern. Inthe basic pattern, the first part of the basic pattern preceding theremaining part of the basic pattern, and a length of the changed patterncorresponds to (R mod X).

According to an exemplary embodiment, the wireless transceiver of the UEmay receive configuration information associated with a D2D datatransmission resource, the configuration information being transmittedfrom an evolved NodeB (eNB). The one or more processors of the UE maydetermine a D2D data transmission resource, the D2D data transmissionresource including a pool of subframes, and select D2D data transmissionsubframes from among the pool of subframes based on a changed pattern,the changed pattern being determined based on (R mod X), wherein Rcorresponds to the number of subframes in the pool of subframes and Xcorresponds to a length of a basic pattern, where R and X are naturalnumbers. The wireless transceiver may transmit, from the UE to anotherUE, D2D data based on the selected D2D data transmission subframes. Alength of the changed pattern may correspond to R.

-   -   The changed pattern may include a first part and a second part,        a length of the first part corresponds to [R/X], and a length of        the second part corresponds to (R mod X).

The second part of the changed pattern may correspond to a partialportion of the basic pattern.

The processors may include an application-specific integrated circuit(ASIC), another chipset, a logic circuit, and/or a data processingdevice. The memories may include a Read-Only Memory (ROM), a RandomAccess Memory (RAM), a flash memory, a memory card, a storage mediumand/or another storage device. The RF units may include a basebandcircuit for processing a wireless signal. When an embodiment is embodiedas software, the described scheme may be embodied as a module (process,function, or the like) that executes the described function. The modulemay be stored in a memory, and may be executed by a processor. Thememory may be disposed inside or outside the processor, and may beconnected to the processor through various well-known means.

In the described exemplary system, although methods are described basedon a flowchart as a series of steps or blocks, aspects of the presentinvention are not limited to the sequence of the steps and a step may beexecuted in a different order or may be executed in parallel withanother step. In addition, it is apparent to those skilled in the artthat the steps in the flowchart are not exclusive, and another step maybe included or one or more steps of the flowchart may be omitted withoutaffecting the scope of the present invention.

What is claimed is:
 1. A user equipment (UE) to transmitdevice-to-device (D2D) data using a D2D data transmission resource,comprising: a wireless transceiver configured to: receive configurationinformation associated with a D2D data transmission resource, theconfiguration information comprising information of a D2D dataallocation period and being transmitted from an evolved NodeB (eNB); andone or more processors configured to: determine a D2D data transmissionresource in each D2D data allocation period, the D2D data transmissionresource comprising a pool of subframes; and select D2D datatransmission subframes from among the pool of subframes based on achanged pattern, the changed pattern being derived from a basic pattern,wherein the wireless transceiver transmits, from the UE to another UE,D2D data based on the selected D2D data transmission subframes, whereinselecting of the D2D data transmission subframes comprises: the one ormore processors is configured to determine, based on whether the numberof subframes in the pool of subframes is less than a length of the basicpattern, the changed pattern based on a value of (R modulo X), wherein Rcorresponds to the number of subframes in the pool of subframes and Xcorresponds to the length of the basic pattern, where R and X arenatural numbers, wherein a length of the changed pattern corresponds tothe number of subframes in the pool of subframes.
 2. The UE of claim 1,wherein: the changed pattern comprises a partial portion of the basicpattern at an end of the changed pattern without having the remainingportion of the basic pattern.
 3. The UE of claim 2, wherein: in thebasic pattern, the partial portion of the basic pattern precedes theremaining portion of the basic pattern.
 4. The UE of claim 1, whereinselecting of the D2D data transmission subframes comprises: determining,based on a determination that the number of subframes in the pool ofsubframes is greater than a length of the basic pattern, the changedpattern by repeating the basic pattern.
 5. The UE of claim 4, whereinthe one or more processors is configured to determine (R modulo X),wherein the changed pattern comprises a first part and a second part,the first part of the changed pattern comprising at least one repetitionof the basic pattern, and wherein a length of the second part of thechanged pattern corresponds to (R modulo X).
 6. The UE of claim 1,wherein: the changed pattern consists of a first part of the basicpattern; in the basic pattern, the first part of the basic patternpreceding the remaining part of the basic pattern; and a length of thechanged pattern corresponds to (R modulo X).